Holographic microscopy records information about the spatial distribution of illuminated objects through their influence on the phase and intensity distribution of the light they scatter. This information can be retrieved from a hologram, at least approximately, by reconstructing the three-dimensional light field responsible for the recorded intensity distribution. Alternatively, features of interest in a hologram can be interpreted with predictions of the theory of light scattering to obtain exceedingly precise measurements of a scattering object's three-dimensional position, size and refractive index. The availability of so much high-quality information about the properties and motions of individual colloidal particles has proved a boon for applications as varied as product quality assessment, microrheology, porosimetry, microrefractometry, and flow velocimetry, as well as for molecular binding assays, and as a tool for fundamental research in statistical physics and materials science.
However, fitting measured holograms to theoretical predictions requires an initial for each scatterer's position. This can pose challenges for conventional image analysis algorithms because the hologram of a small object consists of alternating bright and dark fringes covering a substantial area in the field of view.